Ferroelectric memories have attracted attention as nonvolatile memories. In particular, it is expected to apply a one-transistor memory cell having a Metal Ferroelectrics Semiconductor (MFS) structure to, for example, a NAND flash memory.
In order to increase the memory capacity of the NAND flash memory, a multi-value operation of a memory cell has been progressed. It is desired to realize the multi-value operation even for the memory cell having the MFS structure.